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shinchan-f5's avatar
May 19, 2020

Issues with incremental config sync cache || Unable to do incremental sync, reverting to full load for device group

I received an error similar to below :


notice mcpd[2789]: 0107168e:5: Unable to do incremental sync, reverting to full load for device group /Common/syncgroup1 device %cmi-mcpd peer-/Common/ from commit id { 4 6390393316259868817 /Common/ } to commit id { 3 6391877370007482801 /Common/ }.


Here, changes pertaining to commit id 3 got executed on the peer device. Undesired change like disabled pool member was enabled which caused impact to the business.


The recommended action says to reduce the size and frequency of the configuration changes made to the BIG-IP system. You may also be able to mitigate this issue by increasing the size of the incremental ConfigSync cache.


While I see the explanation below saying if incremental sync cache size exceeds 1024, the BIG-IP performs a full sync which is not happening in my case.


In the Maximum Incremental Sync Size (KB) field, retain the default value of 1024, or type a different value. This value specifies the total size of configuration changes that can reside in the incremental sync cache. If the total size of the configuration changes in the cache exceeds the specified value, the BIG-IP system performs a full sync whenever the next config sync operation occurs.


Can anyone help me understand the below concerns.

Q. Why the full sync doesn't happen if the incremental sync cache size goes beyond 1024. Also it caused an impact to the traffic by configuring changes specific to commit-id 3.


Also I checked below command,

show cm device-group <sync_group> incremental-config-sync-cache


It shows multiple commit id and related configuration,

Q. Is there a procedure to only keep the recent commit-id and flush the old ones so the cache doesn't go beyond default 1024KB.


Q. Can the modify the cache value to the suggested 2048 and will there be any impact of it ? And will it require increasing it in future if say again the cache fills up ?

modify cm device-group <sync_group> incremental-config-sync-size-max ?

Specifies the maximum size (in KB) to devote to incremental config sync cached transactions. Range: 128-10240. Default:1024.


Q. Is there a way we can monitor this proactively (leaving aside the preventive measures of reducing size and frequency of config changes).


Hope I will get answers to the above concerns.


thank DevCentral Community in advance !!!


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